B4C/hBN复相陶瓷与球墨铸铁配副摩擦学性能研究

本文中以热压烧结法制备不同hBN质量分数(0%、10%、20%和30%)的B4C/hBN复相陶瓷作为销试样,与球墨铸铁(QT)盘试样在空气润滑条件下进行销-盘式摩擦磨损试验,滑动速度为0.66 m/s,磨程为850 m,载荷为5 N.借助扫描电子显微镜(SEM)观察摩擦表面和磨屑的形貌特征,利用X光电子能谱(XPS)、X射线衍射(XRD)等分析手段表征磨面和磨屑的物质组成,得出复相陶瓷成分、试验参数对配副摩擦学性能的影响.研究表明:hBN质量分数为0%和10%的复相陶瓷(BN00、BN10)与铸铁配副时,磨损机制以黏着磨损为主,摩擦系数为0.5,h BN质量分数为20%和30%的复相陶瓷(BN20、BN30)与铸铁配副时,陶瓷销表面出现连续的表面膜,该表面膜主要由Fe_2O_3、Fe_3O_4、B_2O_3、B_4C及h BN等物质组成,摩擦系数降低至0.2;随着载荷的升高,QT-BN00与QT-BN10配副磨损机制仍以黏着磨损为主,摩擦系数与5 N载荷无明显变化,而QT-BN20与QT-BN30配副摩擦系数随载荷上升而升高,当载荷为10 N时,摩擦系数升至0.6.

Tribological Behavior of B4C/hBN Ceramic Composites Sliding against Ductile Iron

Boron carbide/boron nitride (B₄C/hBN) ceramic composites, prepared by hot-pressing sintering as pin samples, were coupled with ductile iron disks (QT) in air on a pin-on-disk tribometer. The influences of mass fraction (0%, 10%, 20% and 30%) of boron nitride and normal loads (5 N, 7 N, 10 N) on tribological performance of each friction couples were investigated. The morphology features of friction surfaces were observed with scanning electron microscope and the compositions of friction surfaces and worn debris were measured by Energy dispersive spectrometer, X-ray photoelectron spectroscopy and X-ray diffraction. The results indicate that, at 5 N load, the friction coefficients of B₄C/hBN ceramic composites with 0% and 10% mass ratio of hBN (BN00, BN10) and QT couples were high up to 0.5. In contrast, when hBN contents reached 20% and 30% (BN20, BN30), the friction coefficient were reduced to 0.2. The tribological mechanism of QT-BN00 couple was mainly adhesive wear and severe plastic deformations was observed on worn QT disk. A continuous surface film was discovered on BN30 worn surface and the main tribological morphology of the coupled grey cast iron was mild micro-cuttings. With the increasing normal load (7 N, 10 N), the wear mechanism of QT-BN00 and QT-BN10 was adhesive wear with comparable friction coefficients to that at 5 N load. However, as test load increased, the film formed on BN30 worn surface was damaged, resulting in the rise of the friction coefficient. The friction coefficient increased to 0.6 at the load of 10 N, indicating that the addition of hBN had no improvement on lubrication.